XSLT, 2nd Edition

Processing Modes

There are four flags that change how regular expressions are evaluated:

s

Regular expressions are evaluated in what the specs refer to as “dot-all” mode. When this flag is used, the dot operator (.) matches any character. Under normal processing (without the s flag), the dot operator matches any character except the newline character (#xA). This flag is useful when you want to match strings that might include a newline character.

Note

Perl and other languages refer to this as “single-line” mode; that’s why the abbreviation for “dot-all” mode is s.

m

Regular expressions are evaulated in multiline mode. By default, the metacharacter (^) matches the start of the entire string, while $ matches the end of the entire string. In multiline mode, ^ matches the start of any line within the string, and $ matches the end of any line within the string.

i

Regular expressions are evaluated in case-insensitive mode. The regular expression "a" matches both "a" and "A".

Note that Unicode issues can complicate this greatly. For example, the XQuery 1.0 and XPath 2.0 Functions and Operators spec gives the example of the Unicode sign for degrees Kelvin (K), which is the letter "K". The combination of regex="k" and flags="i" matches the Kelvin sign as well as the letters "k" (k) and "K" (K).

Other Unicode characters don’t convert to letters. For example, the Unicode symbol for the Roman numeral I (Ⅰ) looks like the letter I, but does not convert to one.

x

All whitespace characters ...